The present invention relates to the determination of wavelength dependent information about optical components.
There are two typical measurement setups as known in the art for determining wavelength dependent information about--or wavelength dependent properties of--optical components such as the wavelength dependent loss e.g. of wavelength division multiplexers (WDMs) or fiber bragg gratings. The first setup comprises a tunable laser source in combination with an optical power meter, and the second setup comprises a broadband light source (e.g. a `white` light source) in combination with an optical spectrum analyzer. These instruments are connected to the input and output of a device-under-test (DUT). This way, e.g. the insertion-loss can be measured as a function of the wavelength. For wavelength dependent return-loss measurements, a return-loss test setup is needed with input for a wavelength variable light source. A detailed description of measurement setups as known in the art for determining wavelength dependent properties of optical components is given by Dennis Derickson in "Fiber optic test and measurement", ISBN 0-13-534330-5, 1998, referenced herein as (1), pages 358 ff.
For certain applications, such as in fiber optic networks, it has been found disadvantageous that all the described techniques require the device under test to be directly accessible `on the workbench`, i.e. that a direct measurement of the actual frequency behavior of the DUT `in situ` is not possible.